Sterilization machine and method for sterilizing packaging containers

ABSTRACT

Sterilization apparatus for sterilizing packaging containers, the sterilization apparatus comprising a first carousel for supporting a plurality of sterilization devices, the sterilization devices being adapted to sterilize an interior of the packaging containers by electron beam irradiation, and a transport system for transporting the packaging containers, the transport system comprising a second carousel coaxial with the first carousel, wherein the first carousel comprises a first rotatable shaft and the second carousel comprises a separate second rotatable shaft coaxial with the first rotatable shaft.

The invention relates to a sterilization apparatus and a method forsterilization packaging containers.

In the food industry it is common practice to pack liquid and partlyliquid food products in packaging containers. Such packaging containerscan for example be made of a plastic material such as for instance PET,or be made of a laminated carton material. With regard to the later acommon type of laminated carton material is the ones that comprises acore layer of paper or paperboard and one or more barrier layers of, forexample, polymer material or aluminium foil. An increasingly commonpackaging type is the “carton bottle” manufactured in a filling machinein that packaging blanks of the above-described packaging laminate areformed and sealed as a sleeve. Said sleeve is closed in one end in thata top of thermoplastic material is injection moulded directly on thesleeve end portion. The sheets of packaging laminate may be cut from amagazine reel of packaging laminate.

Before the packaging container is filled with the food product, inparticular if filling takes place at ambient temperature, the packagingcontainer needs to be sterilized. Sterilization is a term referring toany process that eliminates or kills microbial life, includingtransmissible agents such as for example fungi, bacteria, viruses andspores, which may be present on a surface of the packaging material orin a product. In the (food) packaging industry this is generallyreferred to as aseptic packaging, i.e. packaging sterilized products insterilized packaging containers, i.e. keeping both the product and thepackaging container free form living germs and microorganisms, so thatthe freshness of the product can be preserved without special coolingrequirements, i.e. so that sterility can be maintained inside apackaging container although it is stored in ambient temperature. Inthis context the term “commercially sterile” is also commonly used andmeans in general the absence of microorganisms capable of growing in thefood at normal non-refrigerated conditions at which the food is likelyto be held during manufacture, distribution and storage. In this patentapplication the word “sterile” refers to a condition being at leastcommercially sterile.

A conventional way of sterilizing packaging containers is a chemicalsterilization, in particular using hydrogen peroxide, preferably in gasphase. However, this process has the drawback that residues of thechemical substance might remain on a surface of the container.

Another known way of sterilizing packaging containers is throughradiation, in particular, using electron beams. EP 2 371 397 A1describes a sterilization machine comprising a plurality ofsterilization devices adapted to be inserted into the containers forsterilizing the interior of the containers. The containers and thesterilization devices are arranged on a common rotary support structurewhich holds the containers and the sterilization devices in a mutuallyaligned position and rotates them along a circular path. The containersare lifted relative to the sterilization devices so that a rod-shapedsterilization element is inserted into the respective container forsterilizing the interior or the container. Another example of asterilization device for sterilization of packaging containers isdescribed in the international application No. PCT/EP2013/076870 filedby the applicant.

Nonetheless, there's still a need to provide an improved sterilizationapparatus and method for sterilizing packaging containers allowing for aparticularly safe and economical sterilization.

The invention proposes a sterilization apparatus according to claim 1and a method for sterilizing packaging containers according to claim 17.Embodiments and several aspects of the invention are defined in thedependent claims and the following description, in particular inconnection with the attached drawings.

The invention will now be further described in connection with theattached drawings in which:

FIG. 1: shows a perspective view of a first embodiment of an inventivesterilization apparatus;

FIG. 2: shows a perspective view of a second embodiment of an inventivesterilization apparatus cut along a plane through the common axis ofrotation of the carousels; and

FIG. 3: shows the upper carousel of FIG. 2 in more detail.

Equal or corresponding elements are denominated by the same referencenumerous in all figures. The features described in connection with thedifferent embodiments can be combined as far as technically possible.Some cross sectional surfaces are provided with dashed-dotted lines.This is to illustrate that a cross section has been made through afeature but that details of the interior of the feature is not shown indetail.

The sterilization apparatus according to the invention for sterilizingpackaging containers comprises a first carousel for supporting aplurality of sterilization devices, the sterilization devices beingadapted to sterilize an interior of the packaging containers by electronbeam irradiation, and a transport system for transporting the packagingcontainers, the transport system comprising a second carousel coaxialwith the first carousel. The first carousel comprises a first rotatableshaft and the second carousel comprises a second rotatable shaft beingspaced apart from the first rotatable shaft. In an embodiment bothshafts may share a common rotational axis.

The term carousel shall include any type of movable device, for exampleconveyor chains or plate, belts, wheels and the like. The movement alonga trajectory of the carousel may comprise a pure rotational movement butis not limited thereto. It may also comprise a translational movement ora combination of rotational and translational movement.

The term “packaging container” shall not be limited to container forliquid or solid food, but is used for convenience purposes only.Generally any container, which needs to be sterilized, is suitable forthis purpose and shall fall under this term, including, but not limitedto, container for medical drugs, for medical devices, for liquid,semi-liquid or solid food, for storing biological material or organicsubstances.

The term “sterilization” in this context means the sterilization of asurface of an object to be sterilized and/or, —if the object contains aninterior part—, the sterilization of said interior part.

The surface of the object may comprise the inner surface of the object,the interior and the outer surface or parts thereof of the object. Theinner surface of the packaging container is the surface being in contactwith food, or general the material to be filled into the container.According to the invention, the plurality of sterilization devices isadapted to sterilize the inner surface and the interior of thecontainer. In a further embodiment it is also adapted to sterilize partof the outer surface of the container.

A basic idea of the invention is to provide separate and/or separatedcarousels for the sterilization devices and the packaging containers,respectively. The first carousel is intended for supporting thesterilization devices and the second carousel is a part of a transportsystem for transporting the packaging containers along a preferablycircular path. The interior sterilization of the containers takes placeduring transportation of the containers along the circular path. Thesecond carousel may for example either hold the containers directly orguide a container conveyor, such as a chain or belt conveyor, along apreferably circular path.

Each of the carousels may comprise a rotatable wheel or plate connectedto a shaft in a rigid manner so that the wheel or plate and the shaftrotate together. The first rotatable shaft can be a drive shaft forrotating the wheel or plate of the first carousel and the secondrotatable shaft is preferably a drive shaft for rotating the wheel orplate of the second carousel.

The separate carousels with separate drive shafts allow for a greaterflexibility of operation and a better utilization of the available spacein the sterilization machine as compared to the known composite carouselwith single drive shaft. Because the carousels are not interconnected bya single common drive shaft, it is generally possible to operate thecarousels independently of each other. Such arrangement allows foradjustment of one of the plate with respect to the other. Moreover, anadditional free space is generated between the carousels, in particularbetween the first and second rotatable shafts, which can be used so thatthe compactness of the machine can be enhanced and/or the arrangement ofcomponents within the machine can be improved.

The sterilization devices are preferably adapted to be at least partlyinserted into a respective packaging container to be sterilized, inparticular through an open top or bottom of the packaging container. Inan embodiment, the sterilization devices is inserted into the containeralong a substantially vertical movement direction during rotation of thesterilization devices and the packaging containers about a commonrotational axis defined by the first and second rotary shafts. It may bepreferred according to the invention that the first carousel is an uppercarousel and the second carousel a lower carousel.

In an embodiment of the invention, the sterilization apparatus comprisesa first driving device for rotating the first carousel. The firstdriving device is adapted to rotate the first drive shaft (first rotaryshaft) and may in particular be a rotary drive and more preferably anelectric motor. The first driving device may be arranged on a stationaryframe element, in particular on a side of the sterilization devicesopposite the second rotational shaft. More preferably, the drivingdevice is arranged in a plane above the sterilization devices.

According to an embodiment the first driving device is adapted to driveand rotate the first and second carousel. For this purpose, the firstdriving device is in operative connection with the first and the secondrotatable shafts. For instance, the first driving device may comprise athird shaft arranged substantially parallel to the first and secondshaft but spaced apart from them. Such shaft may be coupled to the firstand/or second shaft by coupling means, i.e. by a conveyor belt, a band,V-belt, chain, gear drive, spiral bevel gear, sleeve or torsion clutchand the like.

The operative connection to any of the shafts may also comprise asynchronizing device for synchronizing the rotation or movement of thefirst carousel with the second carousel and vice versa.

In an alternative embodiment of the invention, the sterilization machinecomprises a second driving device for rotating the second carousel. Thesecond driving device is adapted to rotate the second drive shaft(second rotary shaft) and may in particular be a rotary drive and morepreferably an electric motor. The second driving device may be arrangedon a stationary frame element, in particular on a side of the packagingcontainers opposite the first rotational shaft. More preferably, themotor is arranged in a plane below a conveying path of the packagingcontainers. In such concept of the invention, the sterilization machinecomprises separate driving devices for driving the first carousel andthe second carousel, wherein a first driving device is adapted to rotatethe first rotatable shaft and a second driving device is adapted torotate the second rotatable shaft.

In an embodiment the second driving device is adapted to drive thesecond carousel independently of the first carousel. In other words, thesecond driving device may be operated independently of the first drivingdevice, so that it is for example possible to rotate the second carousel(with the sterilization devices) while the first carousel is standingstill. The advantage of this embodiment is that an overheating of thepackaging containers by the sterilization devices can be efficientlyprevented in case of an interruption of the movement of the containers.It is in particular not necessary to stop the operation of thesterilization devices which are generally and preferably operatedcontinuously.

For sterilization purposes, i.e. during regular operation of thesterilization apparatus, the sterilization apparatus may comprisesynchronization device for synchronizing a rotational movement of thefirst carousel and the second carousel. The synchronization device isadapted to synchronize the speed of the first and second carousel andmaintain a relative fixed position such that the longitudinal axes ofthe packaging containers and the sterilization devices are aligned. I.e.a longitudinal axis of each packaging container is aligned with alongitudinal axis of one of the sterilization devices. The packagingcontainers and the sterilization devices are preferably transportedalong a sterilization path with their respective longitudinal axis beingaligned with each other. The sterilization path is at least partlycircular.

The synchronization device is preferably adapted to be switched on andswitched off, i.e. be put in operation and out of operation, preferablythrough a control unit and/or by an operator. In normal operation it maybe used to keep the position of packaging containers aligned with theposition of sterilization device and may be controlled by a control unitcomprising sensors for measuring the positions and calculation unitsusing feedback loops to achieve such alignment. The synchronization canbe turned off in case of an unintentional interruption of the transportsystem transporting the packaging containers, such that thesterilization devices may keep rotating even during a downtime of thetransport system, i.e. a standstill of the packaging containers. Thecontrol unit for controlling the synchronization device is preferablyadapted to prevent the sterilization devices to be standing still whilethey are operating, i.e. they are either turned off or they are keptrotating.

In order to provide the possibility to interrupt the synchronization ofthe carousels, there is preferably no permanent and/or forcedsynchronisation, in particular no permanent and/or rigid mechanicalconnection interconnecting—for a synchronized movement of thecarousels—the first and second carousels.

The independent rotation of the sterilization devices also allows fortesting the sterilization devices before a start up of the sterilizationmachine and/or during an interruption. Such testing can, for example, bedone by passing the rotating sterilization devices along a stationarysensor device arranged on the sterilization machine while the packagingcontainers are not moving.

In another embodiment of the invention the first rotatable shaft isconstructed as a hollow shaft having an interior channel for receivingat least one utility line for the sterilization devices and adistribution chamber is arranged at an end of the first rotatable shaftfacing the second rotatable shaft.

The distribution chamber may comprise a housing and at least one exitopening for a utility line. This embodiment allows for an easyconnection of the sterilization devices to a utility system, for examplean electrical system, and/or a cooling system, and/or a datacommunication system. The utility lines or supply lines may be routedfrom the sterilization devices to the utility system through the centralrotatable shaft of the first carousel, in particular via thedistribution chamber.

Utility lines may comprise an electrical connection, like one or morewires for electrical current or a connection for a cooling medium, i.e.a pipe. The utility line or lines are coupled to a utility system on oneend of the shaft and to the sterilization devices. There might be aplurality of individual utility lines routed through the shaft, each ofthose assigned to one of the plurality of sterilizing devices.Alternatively there might be a common utility line, i.e. for a coolingmedium routed through the shaft. Said common utility line might beseparated in the distribution chamber to supply the individualsterilization devices.

In another embodiment, a distribution device for distributing at leastone utility to the sterilization devices is arranged within thedistribution chamber. The distribution device may be connected to theutility line from the shaft. The distribution chamber preferablyencloses the distribution device such that it is separated from asterilization chamber or zone where the electrons exit the sterilizationdevices and where the sterilization takes place.

In an embodiment, the distribution chamber closes and covers theinterior channel of the first rotatable shaft towards the sterilizationzone so that the introduction of non-sterile elements (dirt etc.) fromthe channel to the sterilization zone is essentially prevented. Thedistribution device can in particular be adapted for distributingutilities such as electricity/power and/or a cooling fluid to therespective sterilization devices. Also data communication can make useof the distribution device for data transfer between the sterilizationdevices and a control unit.

In a particularly embodiment, the housing of the distribution chambercompletely encloses the distribution chamber on the first side of thecarrier plate. By that, the channel of the first rotatable shaft and/orthe interior of the distribution chamber has no direct connection to thesterilization zone on the first side of the carrier plate.

In yet another embodiment of the invention, the distribution deviceincludes a swivel. The swivel, which comprises a rotary connectionbetween two elements of the distribution device, has at least one inletconnection for a utility line from the utility system and one or moreoutlet connections for a utility line (utility lines) to the respectivesterilization devices. The swivel allows for a rotational movement ofthe inlet connection relative to the outlet connection. Therefore, theat least one utility line routed through the channel of the firstrotational shaft can be stationary, while the utility lines to thesterilization devices can rotate.

In another embodiment of the invention, the first carousel comprises arotatable carrier plate which carries the sterilization devices. In oneembodiment, the sterilization devices can be attached to the carrierplate on first side facing the second carousel.

Alternatively the distribution chamber is arranged at a first side ofthe carrier plate facing the second carousel and the sterilizationdevices are arranged at least partly on a second side of the carrierplate. For instance, a first portion of each of the sterilizationdevices can be arranged on the first side, a second portion is arrangedon a second side of the carrier plate opposite the first side. By thisarrangement, the carrier plate separates the distribution chamber from aportion of the sterilization devices, allowing using additional spacefor the devices, otherwise occupied by the distribution chamber.

The second side of the carrier plate which can be regarded a non-sterilearea, may therefore receive the utility lines for the sterilizationdevices. In the particular embodiment disclosed earlier, thesterilization devices are preferably attached to the carrier plate suchthat they extend through the carrier plate and an electron exit windowis arranged on the first side of the carrier plate and a power device ofthe sterilization device, in particular a high voltage power device, isarranged on the second side. A connection interface for connecting tothe utility line is preferably arranged on the second side of thecarrier plate. The connection interface of the sterilization device may,for example, include an electrical interface and/or an interface for acooling fluid.

In another embodiment, the distribution chamber is cup-shaped and/or hasa conical shape. A lower-diameter portion of the distribution chamberpreferably faces the second carousel and a larger-diameter portion ofthe distribution chamber preferably faces the first carousel, inparticular the carrier plate. The larger-diameter portion of thedistribution chamber preferably has a diameter which is greater than anouter diameter of the first rotatable shaft.

The carrier plate is preferably provided with one or more through-holesproviding a connection between the interior of the distribution chamberand the second side of the carrier plate. The at least one through-holeis preferably located in a diameter portion of the carrier plate betweenthe outer circumference of the first rotatable shaft and the innercircumference of the distribution chamber housing in contact with thecarrier plate. Alternatively the distribution chamber may compriseopening or through holes at positions aligned with positions of thecarrier plate. By this arrangement, utility lines may easily be routedthrough the first rotatable shaft to the first side of the carrier plateand back to the second side where they can be connected to thesterilization devices.

The distribution chamber may be provided with a radiation shielding, inparticular against X-rays. In the following, the term X-ray includes allkinds of electromagnetic radiation and emissions generated duringoperation of the apparatus, including but not limited to electroncollision radiation. The housing of the distribution chamber can forexample be constructed from a shielding material such as lead, tungsten,steel or an alloy thereof. The shielding provides a protection of theelements arranged within the distribution chamber such as thedistribution element from radiation during operation of thesterilization devices. In addition, the radiation shielding may alsoprovide an efficient radiation protection of the power device, inparticular if the radiation shielding has a conical shape.

In another embodiment, at least one fixed second sterilization device isarranged between the first carousel and the second carousel, inparticular for sterilizing an outer surface of the packaging containers.The second sterilization device may in particular be arranged along aconveying path of the packaging containers and extend along an entry orexit point of the packaging containers to or from the second carousel.In or more embodiments two second sterilization devices are arrangedwith their electron exit windows facing each other. They are arranged ata distance from each other such that a gap for packaging containers areformed between them. Their electron clouds form a unified electron cloudfilling the gap. The packaging containers are transported in the gap andare thereby sterilized on their outer surface. In one or moreembodiments only one second sterilization device is provided, and thepackaging container are rotated around their own axes when passing theelectron exit window, in order to obtain full sterilization of the outersurface. The second sterilization devices may be stationary.

In a embodiment the at least one second sterilization device is adaptedto perform an exterior sterilization of the packaging containers a leastpartly overlapping with the interior sterilization. That means an areaof the at least one second sterilization device, in which an object issterilized overlaps at least partly with an area, in which an object issterilized by one of the plurality of first sterilization devices.Therefore, the second sterilization device extends at least partlybetween the first carousel and the second carousel and may also at leastpartly extend between the first rotatable shaft and the second rotatableshaft. In such embodiment the at least one second sterilization deviceis arranged at least partly in the space between the first and secondshaft.

A simultaneous interior and exterior sterilization can be achieved inthat the second sterilization device is adapted to create asterilization cloud of electrons at least partly overlapping with asterilization cloud of a first sterilization device.

The second sterilization device preferably has a longitudinal axis beinginclined to the rotational axis of the first and/or the second rotatableshaft, for example between 45 degree and 90 degree, or more particularbetween 60 degree and 80 degree. In an embodiment is substantiallytransversal to the rotational axis.

Another aspect of the invention is related to a method for sterilizing aplurality of packaging containers, the method comprising the steps ofrotating a first carousel supporting a plurality of sterilizationdevices which are adapted to sterilize an interior of the packagingcontainers by electron beam irradiation, and transporting the packagingcontainers by means of a transport system comprising a second carouselwhich is coaxial with the first carousel, wherein the first carouselcomprises a first rotatable shaft, the second carousel comprises aseparate second rotatable shaft coaxial with the first rotatable shaftand the first carousel is rotated by means of a first driving deviceconnected to the first rotatable shaft for rotation thereof. The methodcan in particular be carried out in an inventive sterilization machineand provides the effects and advantages discussed in connectiontherewith.

FIG. 2 illustrates a first embodiment of the invention. Thesterilization apparatus 10 comprises a frame (not shown) having an uppersupport element 16 and a lower support element 18. A first carousel 20,which in the shown embodiments is an upper carousel, is supported by theupper support element 16. A second carousel 40, which is a lowercarousel, is supported by the lower support element 18. The uppercarousel 20 and the lower carousel 40 are rotatable about a commonrotation axis 4, which is a vertical axis.

The first carousel 20 comprises a rotary carrier plate 22 which supportsa plurality of first sterilization devices 50 that are adapted tosterilize an interior of a packaging container 2 by electronirradiation. The first sterilization devices 50 are arranged on acircumference of the carrier plate 22 which is preferably a circularplate. The first carousel 20 further comprises a first rotatable shaft28. Shaft 28 is connected on one side to the carrier plate 22 in a fixedmanner and coupled with its housing on the other side to support element16. Thus, first rotatable shaft 28 is supported by the upper supportelement 16 in a rotatable manner.

The first rotatable shaft 28, which can also be called a drive shaft, isdriven by a first driving device 32 in a rotating manner. First drivingdevice 32 is coupled to shaft 28 by a conveyor band 14 having teeth,griping into a tooth wheel attached to shaft 28. Therefore, the carrierplate 22 can be rotated through operation of the first driving device32. The first driving device 32 is mounted on the upper support element16 of the frame.

The second carousel 40 comprises a rotary wheel or plate 42 for guidingand/or transporting the packaging containers 2 along a circulartransportation path such that each container can be aligned with one ofthe sterilization devices 50 during its transportation along thetransportation path. The wheel 42 can be a rotary carrier or guide wheel42. It can for example directly hold the packaging containers 2 or as inthis embodiment be engaged with a conveyer 12 which conveys and/or holdsthe packaging containers 2.

A second rotatable shaft 44 is connected to the wheel 42 in a fixedmanner. The second rotatable shaft 44, which can be called a seconddrive shaft, is driven by a second driving device 46 in a rotatingmanner. The second driving device is connected to second shaft 44 in asimilar manner as the first driving device. Therefore, through operationof the second driving device the guide wheel 42 can be rotated. Thesecond driving device 46 is mounted to the lower support element 18 ofthe frame 14. The second rotatable shaft 44 is supported in a rotatablemanner by the lower support element 18. As can be seen from FIG. 2, bothdriving devices are mounted on the respective plates facing outwards.

In this embodiment, the first rotatable shaft 28 and the secondrotatable shaft 44 are coaxial with each other and rotate about a commonrotation axis 4. Carrier plate 22 is connected to a lower end portion ofthe first rotatable shaft 28, and wheel 42 is connected to an upper endportion of the second rotatable shaft 44. The shafts 28, 44 areseparated by a gap. The distance between the shafts 28 and 44corresponds to at least the height of the packaging containers 2,preferably at least twice the height of the packaging containers 2. Thefirst carousel 20 and the second carousel 40 can be driven independentlyof each other by the respective driving devices 32 and 46.

The sterilization apparatus 10 further comprises a synchronizationdevice (not shown) for a synchronizing the rotational movement of thefirst carousel 20 with the rotational movement of the second carousel 40or vice versa. Such synchronization device can for example be amechanical synchronization device. However, the synchronization devicecomprises preferably a control unit, which measures any deviation in thealignment. That can be done for example by measuring the positionbetween the first and second carousel, either directly or indirectlyusing the position of the sterilizing elements and the containers. In anexample sensors are continuously measuring position markers on the wheel42 and plate 22 to compare those with a set position. Any deviationresulting from said measurement is fed to the control unit forprocessing. Alternatively or in addition, rotational speed can bemeasured.

The control unit comprise one or more feedback loops to compensate thedeviation and synchronize the operations of the first and second drivingdevice 32, 46. In operation, one of the devices may accelerate ordecelerate as to reduce any measured deviation until the position ofsterilizing devices and containers are realigned.

In addition, the synchronization device is adapted to be put out ofoperation so as to allow the first carousel 20 and the second carousel40 to be driven independently of each other. Therefore, the firstcarousel 20 and the second carousel 40 can be selectively driven in asynchronized manner or in a non-synchronized manner. In particular, itis also possible to only drive one of the carousels i.e. only the firstcarousel 20 and/or only the second carousel 40.

In the following one of the first sterilization device 50 will bedescribed with reference to FIG. 3. The first sterilization devices 50are substantially constructed in the same manner so that the followingdescription applies to the other first sterilization devices 50 as well.The first sterilization device 50 comprises an electron beam emitter 52for emitting an electron beam and a power device 66 adapted to provide ahigh voltage power to the electron beam emitter 52. The electron beamemitter 52 comprises a hermetically sealed vacuum chamber 54, anelectron beam generator 56 arranged in the vacuum chamber 54 forgenerating an electron beam, and an electron exit window 58 at alongitudinal end of the vacuum chamber 54.

The vacuum chamber 54 has housing 60 having an elongate and inparticular substantially cylindrical shape. The housing 60 comprisesfirst housing part 62 having a smaller cross-section and a secondhousing part 64 having a larger cross-section. The electron beamgenerator 56, which comprises a heatable filament and/or a cathode, isarranged in the second housing part 64. The cylindrical first housingpart 62, which may be described as rod-shaped, is adapted to provide anelectron acceleration zone between the electron beam generator 56 andthe electron exit window 58. The electron exit window 58 is located atan end surface of the first housing part 62. The second housing part 64contains an electrical interface for connection to the power device 66.The second housing part 64 of the electron beam emitters 52 and thepower devices 66 are directly connected to each other and aredistributed around the first rotatable shaft 28.

In use, the electron beam is generated by heating the filament. When anelectrical current is fed through the filament, the electricalresistance of the filament causes the filament to be heated to atemperature in the order of 2000° C. This heating causes the filament toemit electrons. The electrons are accelerated towards the electron exitwindow 58 by means of a voltage potential between the cathode and theelectron exit window 58 which constitutes the anode. Subsequently, theelectrons pass through the electron exit window 58 and continue towardsa target area, i.e. in this case the inside of the packaging container2. Particular, the electrons generate and electron cloud around exitwindow 58 due to energy loosing scattering effects.

The voltage potential between the cathode and the electron exit window58 is created for example by connecting the cathode and the filament tothe power device 66 and by connecting the housing 60 including theelectron exit window 58 to ground. The filament is also connected to thepower device 66 for providing an electrical current through thefilament. The voltage between the cathode and the electron exit window58 may be in the order of 75 to 150 kV.

Carrier plate 22 has a plurality of mounting holes arranged with aregular spacing around the rotational axis 4. The electron beam emitters52 extend through the mounting holes such that the first housing part 62with exit window 58 protrudes on a first side 23 of carrier plate 22,the lower side. The second housing part 64 as well as the power device66 is arranged on a second side 24 of carrier plate 22, the upper side.In an alternative embodiment, carrier plate 22 may contain mountingholes suitable to receive also the second housing part 64, therebyseparating power device 66 on the upper side from the beam emitters 52.In such embodiment carrier plate 22 also contains a shielding materialto prevent radiation emitting into an area above the upper side. Carrierplate 22 comprises steel or another suitable stable material to sustainmechanical forces which can occur during operation.

During a sterilization cycle the first housing part 62 of thesterilization device 50 is inserted into the packaging container 2through an opening thereof for sterilizing the interior of the packagingcontainer 2.

As illustrated in FIG. 1, a lifting device 48 (only partly shown) isprovided for moving the packaging containers 2 along a verticaldirection towards and away from the first sterilization device 50. Thesterilization device 50 is inserted into a packaging container 2 duringthe movement of the packaging container 2 together with the guide wheel42. The guide wheel 42 is rotating synchronously with the carrier wheel22. Each packaging container 2 is synchronously moved with a firststerilization device 50, thereby keeping the longitudinal axis of thefirst sterilization device 50 aligned with a longitudinal axis of thepackaging container 2.

During the vertical movement of container 2, the inner surface ofcontainer 2 is sterilized all the way down to the far end of container2. The emitted electrons generate and electron cloud around exit window58 due to energy loosing scattering effects. Every surface part ofcontainer 2 passing through said cloud and remaining there for a certainperiod of time is sterilized. As such electron beam emitter 52 may notonly be used to sterilize the inner surface an interior of container 2,but also a portion of the outer surface, particular close to the openingof container 2.

The period of time (sterilization time) a part of the surface of thecontainer has to remain within the electron cloud generated by electronbeam emitter 52 must be sufficiently high to eliminate allmicrobiological substances. In other words each part of the container tobe sterilized must be exposed to a sufficiently high dosage. Such dosage(and the corresponding sterilization time) may depend inter alia fromthe speed of the movement between electron beam emitter 52 and packagingcontainer 2, the electron voltage, the electron current, gas compositionand density within and around the container, diameter or distancebetween of the beam emitter and container, shape of the container andthe electron distribution through the exit window.

The first rotatable shaft 28 is constructed as a hollow shaft having achannel 30 extending longitudinally along the shaft. The first rotatableshaft 28 is arranged on the second side 24 of the carrier plate 22, i.e.in this case the upper side. The power device 66 is also arranged on thesecond side 24 of the carrier plate 22, i.e. on the same side as thefirst rotatable shaft 28. The channel 30 communicates with the firstside 23, i.e. the lower side, of the carrier plate 22. The carrier plate22 has a central through-hole coaxial with the first rotatable shaft 28.

A distribution chamber 34 is arranged on the first side 23 of thecarrier plate 22, at a longitudinal end of the first rotatable shaft 28,in particular under the first rotatable shaft 28. The distributionchamber 34 comprises a substantially cup-shaped housing which preferablycompletely closes the channel 30 on the first side 23 of the carrierplate 22. In other words, there is no connection between the channel 30and the sterilization zone which extends on the first side 23 of thecarrier plate 22. The distribution chamber 34 has a first openingtowards the channel 30 and at least one second opening towards thesecond side 24 of the carrier plate 22, in particular in a zone radiallyoutside of the first rotatable shaft 28. The carrier plate 22 has aplurality of through-holes 26 in an area surrounding the first rotatableshaft 28 so as to provide a passage between the interior of thedistribution chamber 34 and the second side 24 of the carrier plate 22.The distribution chamber 34 provides a passage from the channel 30 tothe second side 24 of the carrier plate 22 via the first side 23,wherein the passage along the first side 23 is preferably completelyclosed by the housing of the distribution chamber 34.

The distribution chamber 34 houses a distribution device 36 fordistributing at least one utility such as electricity and/or a coolingfluid to the first sterilization devices 50. The distribution device 36comprises a swivel in order to distribute the at least one utility froma non-rotating utility line to the rotating sterilization devices 50.The distribution of the utility, in particular electricity, can also beachieved with at least one slip ring. In particular for the protectionof the distribution device 36 the housing of the distribution chamber 34can be provided with a radiation shielding 35, in particular againstX-rays which are generated by the electron beam emitters 52. Theradiation shielding 35 can be done in a generally known manner, forexample using materials such as lead, tungsten or alloys thereof.

The first sterilization devices 50 are continuously operated, i.e. theelectron emission is not shut off between sterilization cycles, i.e. itis kept in operation also in between two packaging containers 2 beingsterilized by the same sterilization device 50. In a preferredembodiment of the invention the sterilization machine comprises asecurity unit adapted to keep rotating the first carousel 20 with thefirst sterilization devices 50 even when the second carousel 40 isstanding still, provided that the first sterilization devices 50 arekept in operation. In other words the security device prevents the firstcarousel 20 standing still while the first sterilization devices are inoperation, thereby preventing overheating of the packaging containers 2.

As illustrated in FIG. 1, sterilization apparatus 10 comprises at leastone second stationary sterilization device 70 in addition to theplurality of rotating first sterilization devices 50. The firststerilization devices 50 are mainly used for interior sterilization andthe at least one second sterilization device 70 is used for partlyexterior sterilization of the packaging containers 2. The secondsterilization device 70 is preferably arranged such that an overlappingsterilization area is provided where simultaneous exterior and interiorsterilization of a packaging container 2 takes place. Sterilizationdevice 70 comprises two beam emitters each having rectangular exitwindows. The second sterilization device 70 is arranged along aconveying path of the packaging containers 2. The exit windows of bothemitters are facing each other and the packaging containers are passingthrough an area between the exit windows. Both emitters of stationarysterilization device 70 are slightly tilted or inclined with respect toa planar plane, meaning their exit windows are not parallel to eachother, and inclined from a vertical plane. Further, the longitudinalaxes of the second sterilization devices are not transversal to thelongitudinal axis of containers 2. As a result, the longitudinal axis ofthe emitters of second sterilization device 70 may have an angle ofabout 45 degree to 90 degree toward rotational axis 4 or thelongitudinal axis of containers 2, preferable between 60 degrees and 80degree. As a result, when containers enter the area covered by theemitter of sterilization device 70, the outer surface close to theopening of containers 2 is sterilized first. Parts of the outer surfacecloser to the far end of container 2 are sterilized when passing throughthe area of both emitters.

By this arrangement the interior and inner surface of container 2 aresterilized first. A common electron cloud and aseptic or sterile zone isgenerated by one of the first sterilization devices and the secondsterilization device at the area where the container enter the secondsterilization device 70.

The inventive sterilization apparatus 10 preferably arranged upstream ofa filling machine for filling liquid or partly liquid food intopackaging containers 2. The packaging containers 2 are conveyed by meansof a conveyer 12 which comprises for example a belt or a chain. At theexit of the sterilization machine 10 the packaging containers aresterile and ready for filling.

The device according to the invention can be arranged in an irradiationchamber in a filling machine. The filling machine comprises at least onefilling station for filling content into the packaging container and atleast one station for sealing the opening after filling. The inventioncan for example be applied in the sterilization device as described inthe international application No. PCT/EP2013/076870 filed by theapplicant. During interior sterilization of the packaging containers arelative movement is made between the packaging container and theemitter. A plurality of emitters are provided on a carousel or the likewhich is adapted to rotate. The packaging containers, which aretransported for example via a conveyor, reach the carousel and areattached to one of the (rotating) emitters. During at least a part ofone rotation of the carousel, the sterilization of the interior surfaceof the packaging container takes place. Then the packaging container isremoved from the appropriate emitter or from the carousel, respectively,and transported into an aseptic chamber for filling and sealing. Theentrance of the aseptic chamber may include emitters for outsidesterilization of the packaging containers.

REFERENCE NUMERALS

-   2 packaging container-   4 rotation axis-   10 sterilization machine-   12 conveyor-   14 belt-   16 upper support element-   18 lower support element-   20 first carousel-   22 carrier plate-   23 first side-   24 second side-   26 through-hole-   28 first rotatable shaft-   30 channel-   32 first driving device-   34 distribution chamber-   35 radiation shielding-   36 distribution device-   40 second carousel-   42 guide wheel-   44 second rotatable shaft-   46 second driving device-   48 lifting device-   50 first sterilization device-   52 electron beam emitter-   54 vacuum chamber-   56 electron beam generator-   58 electron exit window-   60 housing-   62 first housing part-   64 second housing part-   66 power device-   70 second sterilization device

1. Sterilization apparatus for sterilizing packaging containers, thesterilization apparatus comprising a first carousel for supporting aplurality of sterilization devices, the sterilization devices beingadapted to sterilize an interior of the packaging containers by electronbeam irradiation, and a transport system for transporting the packagingcontainers, the transport system comprising a second carousel coaxialwith the first carousel, wherein the first carousel comprises a firstrotatable shaft and the second carousel comprises a separate secondrotatable shaft coaxial with the first rotatable shaft.
 2. Sterilizationapparatus according to claim 1, wherein the sterilization apparatuscomprises a first driving device for rotating the first carousel. 3.Sterilization apparatus according to claim 2, wherein the first drivingdevice is coupled by an operative connection to the second rotatableshaft for synchronously driving the first and second rotatable shafts.4. Sterilization apparatus according to claim 2, wherein thesterilization apparatus comprises a second driving device for rotatingthe second carousel.
 5. Sterilization apparatus according to claim 1,wherein the sterilization apparatus comprises a synchronization meansfor synchronizing a rotational movement of the first carousel and thesecond carousel.
 6. Sterilization apparatus according to claim 1,wherein the first carousel comprises a carrier plate, attached to therotatable shaft close to an end portion of the rotatable shaft, whereinthe a plurality of sterilization devices are attached to the carrierplate.
 7. Sterilization apparatus according to claim 1, wherein thefirst rotatable shaft is constructed as a hollow shaft having aninterior channel for receiving at least one utility line for thesterilization devices.
 8. Sterilization apparatus according to claim 1,further comprising: a distribution chamber is arranged close to an endportion of the first rotatable shaft facing the second rotatable shaft.9. Sterilization apparatus according to claim 8, wherein thedistribution chamber is arranged on a first side of the carrier plateand the plurality of sterilization devices are mounted on a second sideof the carrier plate.
 10. Sterilization apparatus according to claim 8,further comprising: a distribution device for distributing at least oneutility to the sterilization devices, arranged within the distributionchamber.
 11. Sterilization apparatus according to claim 10, wherein thedistribution device includes a swivel.
 12. Sterilization apparatusaccording to claim 9, wherein the distribution chamber comprise at leastone opening towards the second side of the carrier plate opposite thefirst side.
 13. Sterilization apparatus according to claim 8, whereinthe distribution chamber comprises a radiation shielding (35), inparticular against X-rays.
 14. Sterilization apparatus according toclaim 1, wherein at least one second sterilization device is arrangedbetween the first carousel and the second carousel for sterilizing anouter surface of the packaging containers.
 15. Sterilization apparatusaccording to claim 14, wherein the second sterilization device extendsat least partly between the first rotatable shaft and the secondrotatable shaft.
 16. Sterilization apparatus according to claim 14,wherein the second sterilization device has a longitudinal axisextending substantially transversely to the rotation axis of the firstrotatable shaft and/or the second rotatable shaft.
 17. Method forsterilizing a plurality of packaging containers (2), in particular witha sterilization apparatus according to claim 1, the method comprising:rotating a first carousel supporting a plurality of sterilizationdevices which are adapted to sterilize an interior of the packagingcontainers by electron beam irradiation, and transporting the packagingcontainers by a transport system comprising a second carousel which iscoaxial with the first carousel, wherein the first carousel comprises afirst rotatable shaft, the second carousel comprises a separate secondrotatable shaft coaxial with the first rotatable shaft and the firstcarousel is rotated by a first driving device connected to the firstrotatable shaft for rotation thereof.